1. Field of the Invention
This invention relates to pistons for internal combustion engines, and in particular to pistons having features for reducing function and slap noise between the piston skirt and cylinder.
2. Description of the Prior Art
During an internal combustion engine cycle, undesirable friction and slap noise often occurs between a reciprocating piston and wall of the cylinder. Typically, as the speed of the engine increases, friction between the piston skirt and cylinder also increases. As a result of the friction, contact marks form on the piston skirt. Various approaches have been taken in an effort to reduce friction and slap noise, including applying low friction coatings to the piston skirt, changing the shape of the skirt, supplying oil to the outer surface of the piston, and including oil grooves in the piston skirt for containing the supplied oil. An example of such a piston including an oil grove is disclosed in the U.S. Pat. No. 7,086,152, assigned to Federal-Mogul Bradford Limited. Although helpful in reducing friction, these approaches have not eliminated the problem of friction and slap noise.